Design and analysis of a complementary structure-based high selectivity tri-band frequency selective surface.

Area of Science:

• Electromagnetics and Applied Physics
• Metamaterials and Metasurfaces
• Microwave Engineering

Background:

• Frequency Selective Surfaces (FSS) are crucial for controlling electromagnetic wave propagation.
• Existing FSS designs often struggle with achieving multi-band operation with sharp roll-offs and stability.
• Novel resonator designs are needed to enhance filtering characteristics in diverse frequency bands.

Purpose of the Study:

• To propose and validate a novel tri-band bandpass frequency selective surface (FSS).
• To achieve high-order filtering responses in distinct frequency bands using a complementary structure.
• To demonstrate stable angular and polarization performance for the proposed FSS.

Main Methods:

• Design of a tri-band FSS comprising three periodic metal arrays separated by dielectric substrates.
• Utilizing a gridded-double convoluted loop (G-DCL) as a hybrid resonator in the middle layer.
• Development of an equivalent circuit model (ECM) for accurate frequency response analysis from 0 to 16 GHz.

Main Results:

• The FSS exhibits three pass-bands centered at 3.79 GHz, 8.34 GHz, and 12.52 GHz.
• Achieved -3 dB fractional bandwidths of 52.8%, 13.7%, and 19.7% for the respective pass-bands.
• Demonstrated quick roll-off, significant out-of-band suppression, and stable performance within a 50° angular range.

Conclusions:

• The proposed tri-band FSS design effectively achieves high-order filtering responses.
• The complementary structure and G-DCL resonator enable distinct resonant frequencies and bandwidths.
• Fabrication and experimental testing confirmed simulation results, validating the FSS design's accuracy and stability.